Many forms of lock have been proposed for locking doors, windows and container lids or covers, to give a few examples. A common one is a padlock used for locking a hasp on one member to a staple on the other. Other locks of many kinds have also been proposed for similar or sometimes quite different purposes, but a general problem always exists when it is desired to provide a lock which is strong and difficult to force, which can be produced economically and which is convenient in use. It is one of the objects of this invention to provide a lock assembly which, whilst being convenient to use, can nevertheless be made very strong and which is very difficult for a thief to force.
According to the invention in one of its aspects a lock assembly is provided which assembly comprises two separable units having respectively a stud and a passage to receive the stud, wherein the assembly includes:
A slide which is carried by one of the units for limited sliding movement relatively thereto and which occupies a space between the stud and a side of the passage when the units are fitted together; PA0 At least one locking element which is movable in a transverse through opening formed in the slide from a release position, in which it engages in a recess formed in one unit which allows movement of the slide and separation of the units, and a locking position in which it engages in a recess formed in the other unit; PA0 A catch element which engages the slide when the units are fitted together and the locking element is in the second said recess so as to lock the units together; and PA0 A lock which is operable by a key to disengage the catch element from the slide and allow separation of the units.
In certain preferred constructions one of the units is in the form of a stud having an annular groove forming one of the recesses and other unit (the lock unit) comprises a circular body in which the slide, which is in the form of a cylindrical sleeve, is mounted for limited sliding movement. The walls of the slide are formed with two (or any other number of) openings in each of which a ball forming a locking element is mounted. In one position of the slide, which it occupies when the lock unit is removed from the stud unit, the balls are free to move outwardly to allow removal of the lock unit from the stud, whereas when the sleeve is in its other position, in which it is held by the locking element, the balls are held in the groove in the stud and lock the units together.
As will appear from the following description, the invention provides a particularly strong lock assembly, one of the advantages of which is that the lock unit is freely rotatable on the stud or its equivalent, when locked thereon, so the mechanism cannot be forced and broken by turning the lock unit, which can be designed to cover and protect the stud unit.